1. Field of the Invention
The invention relates to a microarray printing device, more particularly to a microarray printing device for printing a microarray of biochemical substance in a biochip.
2. Description of the Related Art
Referring to FIG. 1, a conventional microarray printing device 6 is shown to comprise a holder 61 and a plurality of printing pins 62 mounted on the holder 61 and formed with split tips 622. The holder 61 is processed to have an upper surface 611 formed with a plurality of parallel guide grooves 612 and a plurality of receiving slots 616 extending downwardly from the guide grooves 612 to a lower surface 615 of the holder 61. Each of the printing pins 62 has a head portion 621 and a shank portion 623. The head portion 621 has a bottom surface that abuts against a groove bottom of the corresponding groove 612. The shank portion 623 extends slidably through the corresponding slot 616.
In use, the holder 61 is activated to linearly move the pins 62 into proximity with a printing substrate 100 so as to start printing. The pins 62 are immediately removed from the printing substrate 100 after the tips 622 have touched the latter to prevent excessive time of contact which will result in excessive release of liquid (generally, volume of one drop liquid is 2 pLxcx9c2 nL) The printing pins 62 are closely arranged in a rectangular pattern so as to achieve the purpose of microarray printing.
However, since the guide grooves 612 are individually processed, their depths are not actually the same. As such, the printing pins 62 are not uniform in height and are not lying on the same planar surface. Thus, some tips 622 of the printing pins 62 are in excessive contact with the printing substrate 100 during the printing process, thereby lowering the printing quality. Furthermore, since the shank portion 623 of each printing pin 62 rubs against the surrounding wall 614 that defines the corresponding slot 616 when the former slides upward and downward along the corresponding slot 616 during the printing process, powdery shavings are produced and are stuck in a gap between the shank portion 623 and the surrounding wall 614, thereby resulting in air blockage, and thereby disabling functionality of the printing pins 62.
Another conventional microarray printing device (not shown) found in the market includes a hollow holder and a plurality of capillary tube-like printing pins hung on a top face within the holder by spring units. Since the cross-sections of the capillary tube-like printing pins are generally small, when the tips of the pins contact the substrate, the tips are subjected to a pressure produced not only by the weight of the shank portions, but also by the biasing forces of the spring units, such that the tips are easily broken.
Therefore, the main object of the present invention is to provide a microarray printing device that is capable of overcoming the aforementioned drawbacks of the prior art.
According to this invention, a microarray printing device comprises an elongate holder and a plurality of printing pins. The elongate holder has a top face, a bottom face, and a plurality of receiving slots extending through the holder in a direction from the top face to the bottom face. Each of the printing pins extends through and is linearly movable in a respective one of the receiving slots in the holder, and has a head portion, a tip portion opposite to the head portion, and a shank portion between the head and tip portions. The shank portion has a surface formed with at least one longitudinal flute extending from the head portion to the tip portion.